The committee voted 23 to 14 to subpoena John Gore, a top Justice Department official, to testify about his role in getting the question added to the census. The committee also approved a subpoena for several documents from the Commerce Department, which oversees the bureau, that could shed light on Commerce Secretary Wilbur Ross’ decision to add the question.

Ross testified before the committee in March, but Rep. Elijah Cummings (D-Md.) accused him of continuing to withhold information from Congress. Gore also sat for a transcribed interview with the committee, but Cummings said Ross declined to answer many questions.

Cummings said in a statement:

The Committee is trying to determine the real reason Secretary Ross added the citizenship question, and the documents and testimony covered by these subpoenas are critical to answering that question. We don’t want thousands of pieces of paper that are already public or extensively redacted. We want the specific priority documents we asked for — unredacted and in full. We have bent over backwards to try to work with the Administration. We identified priority documents, we extended deadlines, and we even offered to review certain documents in camera. But the Trump Administration’s stonewalling has left the Committee no choice but to obtain this information by compulsory process.

Cummings said the subpoenas had all been served Tuesday evening.

Ross released a statement Tuesday saying he had already turned over much information to the committee.

The Department remains committed to an open and responsive relationship with the Committee and has been nothing but cooperative with the Committee’s expansive and detailed requests for records. As of today, we have turned over 11,500 pages of documents to the Committee, and I voluntarily testified in front of the same Committee for nearly seven hours on this issue two weeks ago.

Republicans on the committee accused Cummings and Democrats of trying to meddle in a case before the U.S. Supreme Court over the citizenship question. The court already blocked plaintiffs in one of the cases from taking a deposition from Ross, and the Republicans accused the Democrats of trying to circumvent that order. Rep. Justin Amash (R-Mich.) was the only Republican to vote with Democrats to authorize the subpoena.

Democrats and civil rights groups accuse Ross and the Trump administration of needlessly and nefariously adding a question on U.S. citizenship to the survey, which goes out to every American household once per decade. They say that adding the question will cause fewer people to self-respond to the survey, which would have severe consequences because census data are used to determine how hundreds of billions of dollars in federal funds are allocated and how electoral districts are drawn.

Ross says his decision to add the question came about after a Justice Department request so that the agency could better enforce the Voting Rights Act. Former Justice Department officials and census groups are skeptical of that justification, noting that the decennial census has not asked about citizenship status since 1950, and the Voting Rights Act was passed in 1965.

Documents made public as part of litigation over the question also undermine Ross’ public rationale. The documents show Ross was interested in adding a question long before the Justice Department requested he do so. The documents also revealed Ross asked the Justice Department to request that the question be added to the census.

Two federal judges have already blocked the Trump administration from adding the question. One judge said that Ross’ public rationale for adding the question was “pretextual” and that the way the question was added ran afoul of federal law. The other judge went even further and said it violated the U.S. Constitution’s mandate that the census count all living persons in the United States.

The Supreme Court is expected to hear the case on April 23 and resolve the issue before the end of June. Census Bureau officials have already prepared two copies of the census questionnaire: one with the citizenship question and one without. The bureau says it will be prepared to print whichever one is appropriate once the Supreme Court rules.

This article has been updated with comment from the Department of Commerce.